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Final Flashcards

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Biology 101 flashcards
1
Q

What is a synonymous or silent mutation? What are the effects on the mRNA and protein?

A

Changes one codon for an amino acid into another codon the codes for that same amino acid; doesn’t alter mRNA or protein

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2
Q

What is a missense mutation? What are the effects on the mRNA and protein?

A

Codon for one amino acid is changed into a codon for another amino acid; can alter protein structure and function differently depending on conservative substitution or nonconservative substitution

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3
Q

What is conservative substitution?

A

Missense mutation where codon changes into a chemically similar amino acid

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4
Q

What is nonconservative substitution?

A

Missense mutation where codon changes into a chemically different amino acid

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5
Q

What is a nonsense mutation? What are the effects on mRNA and protein?

A

Codon for one amino acid is changed into a stop codon; results in shortened mRNA by the premature stop codon and a typically incomplete, nonfunctional protein

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6
Q

What happens with a base addition?

A

Newly synthesized strand slips and the extra base loops out and is stabilized by repetitive sequences and is added with more replication

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7
Q

What happens with a base deletion?

A

Template strand slips and extra base loops out and is stabilized by repetitive sequences and is deleted with more replication

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8
Q

What is a somatic mutation?

A

Mutation in cells that do not form gametes and therefore cannot be passed on to offspring

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9
Q

What are germinal mutations?

A

Mutation in cells that form gametes (egg or sperm) and can therefore be passed on to offspring

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10
Q

What are mutagens?

A

Factors that increase the mutation rate above the spontaneous rate and disrupt genes involved in the control of cell growth and proliferation

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11
Q

Mutations can be induced by…?

A

Chemicals, x-rays, UV light

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12
Q

What are tautomers?

A

Isomers that differ in the position of their atoms and in the bonds between atoms

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13
Q

What are transition mutations?

A

Purine to purine or pyrimidine to pyrimidine base

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14
Q

What is endocytosis?

A

The internalization of sections of the plasma membrane crucial in allowing neurons to communicate by secreting neurotransmitters

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15
Q

What is depurination?

A

Loss of a purine base that is subsequently replaced with another purine base (results in mutations like GC-AT or AT-GC)

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16
Q

What is deamination?

A

Converts cytosine to uracil (results in CG-TA mutation)

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17
Q

What are examples of spontaneous mutations?

A

Mismatched bases, slippage, depurination, and deamination

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18
Q

What are base analogs?

A

Chemical compounds that are similar in nitrogen bases of DNA and can be incorporated into DNA

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19
Q

What is 5-bromouracil?

A

An analog of thymine that forms an ionized tautomer that pairs with guanine (produces TA-CG or CG-TA transitions)

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20
Q

What is 2-amino-purine?

A

An analog of adenine that normally pairs with thymine that can protonate and pair with cytosine (produces AT-CG or GC-AT transitions)

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21
Q

What are intercalating agents?

A

Planar chemicals that insert in between the stacked bases in the double helix like ethidium bromide that causes insertions or deletions

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22
Q

What is ultraviolet light?

A

Induces formation of covalent bonds between adjacent pyrimidines in DNA

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23
Q

What is ionizing radiation?

A

Produces ionized and highly reactive molecules that chemicals alter DNA bases and lead to mutations

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24
Q

What are examples of reactive molecules?

A

OH, O2, and H2O2

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25
Q

How are mutations prevented?

A

Superoxide dismutase, an enzyme, converts superoxide O2 radicals in H2O2 then catalase converts H2O2 to H2O

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26
Q

What is base-excision repair?

A

Corrects non-bulky damage to individual bases

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27
Q

How does base-excision repair work?

A

DNA glycosylase cleaves base-sugar bonds which creates apurinic or apyrimidinic sites then AP endonucleases recognize DNA strands lacking a nitrogenous base and nick the damaged DNA and deoxyribophosphodiesterase enzyme then excises the damaged DNA region and finally DNA polymerase fills in the gap with complementary nucleotides and DNA ligase seals the nucleotides into the backbone

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28
Q

What is nucleotide-excision repair?

A

Corrects bulky adducts that distort the DNA helix or damage affecting more than one base

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29
Q

How does nucleotide-excision repair work in bacteria?

A

uvrA, uvrB, and uvrC genes form a multi enzyme couples that repairs DNA where uvrA and uvrB proteins assemble and identify DNA damage via distortions in the helix and uvrB binds to DNA at the damage and uvrA is released then uvrC binds to uvrB to form a dimer which cuts nucleotides on either side of the DNA damage; DNA helices removes excised DNA segment and gap is filled by DNA polymerase and DNA ligase

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30
Q

What is mismatch repair?

A

Repair of mismatched bases by recognizing mismatched base pairs, determining which base is incorrect, and removing the mismatched base and repairing the DNA

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31
Q

What are mutator genotypes?

A

Bacteria can have defects in their mutation repair systems which lead to high rates of mutation

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32
Q

How does cancer result?

A

Disruption of the balance between cell proliferation and cell death

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33
Q

What is G1?

A

Longest gap between mitosis and synthesis that accumulates nutrients and transcript proteins

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34
Q

What is G0?

A

Resting phase

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35
Q

What is S?

A

DNA synthesis occurs and there are visible sister chromatids

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36
Q

What is G2?

A

Gap between DNA synthesis and mitosis where cell is producing necessary transcripts and proteins for mitosis

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37
Q

What is mitosis?

A

Cell division in somatic cells to produce identical daughter cells

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38
Q

What is the cell cycle regulated by?

A

Cyclins and cyclin-dependent kinases (Cdks)

39
Q

What do Cdks do?

A

Bind to cyclins and modify the activity of other proteins via phosphorylation

40
Q

How does regulation of cell proliferation happen?

A

Cyclin E determines if a cell leaves G1 and enters S; If a cell decides to divide then cyclin E levels will increase late in G1; Cyclin E interacts with cdk2 to form an active complex; Rb protein (a tumor suppressor) binds to the E2F transcription factor (oncogene) keeping it inactive; Cyclin E-Cdk2 phosphorylate Rb protein which releases E2F; E2F induces transcription of DNA synthesizing enzymes necessary for cells to enter S phase

41
Q

What are oncogenes?

A

Dominant mutant genes that stimulate cell division or block apoptosis

42
Q

What are tumor suppressors?

A

Genes that stop cell division or induce apoptosis

43
Q

What are transvehrsion mutations?

A

A purine to pyrimidine base or vice versa

44
Q

How can deletions result?

A

From breakage and rejoining of a single chromosome or at different positions in homologous chromosomes, from recombination between repetitive DNA at different locations on homologous chromosomes, and recombination between direct repeats in a single chromosome

45
Q

What is an example of unequal crossing over?

A

Williams syndrome when the 17 genes in between the PMS genes is deleted

46
Q

What are terminal deletions?

A

Deletions on the end of the chromosome

47
Q

What are interstitial deletions?

A

Deletions in middle regions along the chromosome resulting in decreased recombination frequency between regions around deleted region

48
Q

How can duplications result?

A

From breakage and rejoining at different positions in homologous chromosomes or recombination between repetitive DNA at different locations on homologous chromosomes

49
Q

What is the result of gene duplications?

A

Altered gene dosage

50
Q

How do inversions result?

A

From breakage and rejoining of a single chromosome or recombination between inverted repeats in a single chromosome

51
Q

What is a paracentric inversion?

A

Inversion along one side of the centromere

52
Q

What is pericentric inversion?

A

Inversion along both sides of the centromere

53
Q

What is reciprocal translocation?

A

Results form breakage and rejoining of non homologous chromosomes or from recombination between repetitive DNA sequences on non homologous chromosomes

54
Q

What are the two types of gametes that result from segregation during meiosis?

A

Adjacent 1 and Alternate

55
Q

What is adjacent 1?

A

Translocation and normal chromosomes segregate together (T1/N2:T2/N1) resulting in inviable cells because there is a gain or loss of genetic material

56
Q

What is alternate?

A

Normal chromosomes segregate together and translocation chromosomes segregate together (T1/T2:N1/N2) resulting in viable cells because there is no gain or loss of genetic material

57
Q

How do translocations result in cancer?

A

Either an oncogene is relocated near a regulatory element, increasing activity or a hybrid oncogene is formed

58
Q

What is euploidy?

A

Variation in the number of complete sets of chromosomes (i.e. multiples of the basic set)

59
Q

What is aneuploidy?

A

Individuals do not have complete sets of chromosomes

60
Q

What is the monoploid number?

A

Basic set of chromosomes (often equal to the haploid number)

61
Q

What are polyploids?

A

General term for multiple sets of chromosomes

62
Q

What happens when you increase the amount of DNA in the cells (i.e. going from diploid to tetraploid)?

A

The cells have to get larger and the nuclei have to get larger to hold the DNA

63
Q

What are autopolyploids?

A

All the chromosome sets are derived from the same original set (i.e. duplicates, triplicates, etc.)

64
Q

What are allopolyploids?

A

Chromosome sets are derived from different, but closely related species (i.e.species hybridize)

65
Q

What does an allotetraploid do?

A

Homeologous chromosomes line up as bivalents

66
Q

What is Turner’s syndrome?

A

Individuals have one X chromosome but lack a second X or a Y; display female phenotype

67
Q

What is Klinefelter syndrome?

A

Individuals have two Xs and a Y; display male phenotype

68
Q

What is Down’s syndrome?

A

Individuals have three copies of chromosome 21

69
Q

Why do we get aneuploidy?

A

Nondisjunction occurs where spindle fibers from one side attach to 2 chromosomes so there is an extra chromosome at one pole in meiosis I or II

70
Q

What is nullisomic?

A

Missing both homologs

71
Q

What is monosomic?

A

Missing one homolog

72
Q

What is trisomic?

A

One extra homolog

73
Q

The chromosome constitution of an allotetraploid can be represented as…

A

2n1 + 2n2

74
Q

A likely explanation for abnormal human phenotype associated with trisomies is…

A

Altered gene dosage

75
Q

What is population genetics?

A

The study of Mendel’s laws and other genetic principles as they apply to populations in order to understand how genetic variation changes through time and space

76
Q

What is theoretical population genetics?

A

Mathematical models of the factors that influence genetic variation within and among populations

77
Q

What is empirical population genetics?

A

Experimental quantification and analysis of genetic variation within and among populations

78
Q

Why is genetic variation important?

A

Because without it, if there were an environmental change then a species would likely go extinct

79
Q

What is a gene?

A

A fundamental unit of inheritance that is encoded in DNA that determines phenotype

80
Q

What is an allele?

A

Alternative forms of a gene that produce distinguishable phenotypes MOST OF THE TIME

81
Q

What is genotype frequency?

A

The proportion of individuals in a population that are homozygotes and heterozygotes

82
Q

What is allele frequency?

A

The proportion of a given allele in a population

83
Q

What is a gene pool?

A

Sum of all alleles in the breeding members of a population at a given time

84
Q

What is heterozygosity?

A

The frequency of heterozygotes in a population

85
Q

What is p^2? 2pq? q^2?

A

Probability of getting homozygous dominant in new offspring in the next generation; heterozygous; homozygous recessive

86
Q

What is the Hardy-Weinberg equilibrium?

A

p^2 + 2pq + q^2 = 1

87
Q

What are the assumptions of HW?

A

Large population, random mating, no mutation, no migration, and no selection

88
Q

What is bottleneck effect?

A

Population is dramatically reduced in numbers due to an event like extreme winters where individuals who survive by chance have a more predominant allele so there can be a change in allele frequency

89
Q

What is the founder effect?

A

A handful of individuals leave the original population and establish a new one so the alleles they carry can be different than the original populations

90
Q

What is genetic drift?

A

Random sampling of genomes that leads to random changes in allele frequency

91
Q

What is inbreeding?

A

Mating between relatives occurs more frequently than expected by chance that results in a loss of heterozygosity or genetic variation

92
Q

What is assortative mating?

A

Mating between individuals with similar phenotypes occurs more frequently than expected by chance

93
Q

When does microevolution occur via natural selection?

A

More individuals are produced each generation than can survive, there’s phenotypic variation among individuals in some trait and has a genetic basis, and there are fitness differences among individuals with different phenotype/genotype

94
Q

What is artificial selection?

A

Changing the phenotype of organisms via domestication or similar methods

Genetics (5 decks)

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